Automatic optimizing pump and sensor system

ABSTRACT

A reciprocating electromagnetic pump comprising a coil wound about a bipolar or tripolar core, a diaphragm structure mechanically coupled to at least one arm with a magnet attached to one end of the arm and a controller electronically connected to the coil. The arm is vibrated under the influence of a periodic electromagnetic field to produce flow. The flow of current through the electromagnet is interrupted so that the magnets are impelled during either a vacuum or a pressure stroke, but are not impelled during the reciprocal stroke. A microprocessor houses the controller which analyzes amplitude and frequency components of a signal produced in the electromagnet coil during the reciprocal stroke to provide a pump flow rate, a pumping efficiency, a pumping load and a height of the fluid column into which the pump mechanism is operating. The controller employs automatic feedback such that an operating frequency is controlled to match a self-resonant frequency of the pump and a coil current is controlled to a minimum value required to provide the desired flow. The microprocessor further comprises a pulse generator and a solid state switch that interrupts current flow through a pump electromagnet.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is continuation-in-part application to Ser. No.09/272,935 filed by the same inventor on Mar. 20, 1999 then entitled “ASelf Optimizing Pump/Sensor System” which application claims the benefitof Provisional Application Number 60/078,743 that was filed on Mar. 20,1998

BACKGROUND OF THE INVENTION

[0002] This invention relates to method devices and system for fludicpumps. More particularly it pertains to /gas pumps, gas flow control andfluid level sensing. This invention optimizes the efficiency ofelectromagnetic reciprocating pumps such as those described in U.S. Pat.No. 4,154,559, U.S. Pat. No. 4,170,439, and U.S. Pat. No. 5,052,904(among others) by control of the pump driving frequency and drivecurrent. Energy savings are realized in the pump operation byeliminating off-nominal pump drive conditions. In practice,electromagnetic reciprocating pumps are driven by the continuous 60 Hzsinusoidal AC service available from utility power companies (50 Hz insome countries other than the US). In their design and manufacture theyare made to pump most efficiently at or near the utility power frequencywhen they are operating at or near the nominal conditions of theirintended application range. As conditions vary from the nominal,efficiency and flow also vary. Off nominal pump performance may becomeso compromised that flow ceases well before the pump capacity isexceeded.

THE PROBLEM

[0003] The problems with prior art pumps is that they do notautomatically optimize. By driving these pumps with periodic pulsesrather than continuous sinusoidal current or by appropriatelyinterrupting a continuous sinusoidal drive current, an opportunity iscreated in the interval when the drive current is off to monitor thevoltage produced in the electromagnet coil by the returning motion ofthe magnet near the core poles. The voltage waveform thus produced canbe analyzed to derive steering information for control of the drivefrequency and drive current to optimize pump operation for varyingconditions that fall within the pump performance limits. In addition,the voltage waveform can be analyzed to indicate the back pressure orpump load. For a given drive current, this indication has a consistentrelationship to the height of the fluid column into which the pump isoperating (based on the Least Squares Fit analysis, this relationship islinear). Thus the pump not only operates as a pump, but also as a levelsensor. This method is scaleable and is applicable to similar pumps withhigher or lesser capacities than those intended for the patent examplesgiven above.

BRIEF SUMMARY OF THE INVENTION

[0004] The invention is the modification of the drive method forelectromagnetic reciprocating pumps such as those described inter aliaby Enomoto U.S. Pat. No. 4,154,559, by Hase U.S. Pat. No. 4,170,439, andby or Itakura U.S. Pat. No. 5,052,904. By driving these pumps withperiodic, pulsed current rather than continuous sinusoidal current, anopportunity is created in the interval between the drive pulses tomonitor the voltage produced in the coil by the motion of the magnet(s)near the core poles.

LIMITATIONS OF THE PRIOR ART

[0005] All the prior art know to the applicant his attorney or theexaminer has been made of record in the parent application to which thisis a continuation in part. The invention enables electromagneticreciprocating pumps to be used to sense the pumping load and, thus,fluid levels. The invention enables control of electromagneticreciprocating pumps to deliver flow at a constant rate under varyingpumping load conditions (varying fluid column heights into which thepump is operating).

[0006] The control of the pump driving frequency and drive current hasbeen achieved manually by manipulating drive frequency and drive currentcontrols while observing the displays of suitable instrumentation andmay be achieved automatically by the incorporation of processing andcontrol elements such as a microprocessor and suitable software.

[0007] The flow-rate-control of Morita's pump '415 is via control of thefrequency at which the ferromagnetic armature is attracted to theelectromagnet poles. There is no teaching in Morita of controlling thedrive current to control flow rate. Morita teaches a controller but thecontroller employs no feedback in its operation. Rather, Morita teachesa controller that is only for control of the operating frequency in a“predetermined” way (column 3, lines 35-41 and in Claim 12, column 9,line 20).

[0008] In Morita's design the ferromagnetic armature compresses theresilient tubing with a force and at a rate that is unmediated byfeedback. The volume of gas or liquid delivered is the internal volumeof the compressed resilient tubing delivered into “free air” ordelivered into an unspecified load. In Morita's design, the flow rate iscontrolled by adjustment of the rate of compression of the tubeirrespective of the pumping load. That is, the volume of fluid or gasdelivered is in some way proportional to the electromagnet drivefrequency because the tube is pinched or compressed more or lessfrequently per-unit-time. In this way the volume of delivered gas orliquid can be “adjusted” but is not manually controlled for optimumpumping efficiency or automatically controlled for optimum pumpingefficiency or for varying load conditions.

[0009] Morita does not teach feedback such that, once adjusted, Morita'spump can produce controlled flow or optimized flow where loadingconditions are varying. Morita also does not teach a signal is producedby the motion of the ferromagnetic armature near the electromagnet.Morita also does not teach how to adjust the operating frequency tomatch the pump self-resonant frequency. Nor does Morita does teach theelectromagnet operating current is adjusted manually or automatically tocontrol flow or to minimize the operating power level for a given flowrate.

[0010] Morita also does not teach the use of any signal which isanalyzed and used to provide control to optimize the operating frequencyto deliver the maximum flow for a given operating power level. Moritaalso does not teach the generation of a signal by the motion of theferromagnetic armature near the electromagnet poles.

[0011] It is very unlikely that the ferromagnetic armature as describedby Morita is able to induce any signal in the electromagnet coil in thatthe armature, as described, is not a magnet (having an independentmagnetic field). The armature as described by Morita is a ferrous platethat shunts the electro-magnetically produced field between the corepoles. This armature/electromagnet design would have no repulsionphasing. That is the armature would be attracted to the electromagnetregardless of the direction of current flow through the electromagnetcoil. Likewise, the armature would be attracted to the electromagnetregardless of the physical orientation of the armature. Hence, thearmature would not exhibit “magnetism” per se with its own “permanent”magnetic field and would not be capable of inducing a voltage in theelectromagnet coil. It is unlikely, therefore, that Morita anticipatedgenerating a signal in the electromagnet coil by the return motion ofthe armature near the coil that could be analyzed to provide feedbackfor control.

[0012] In summary Morita does not teach how to optimize the pumpingefficiency by control of the drive current. Morita also does not teachthat any signal that is generated and used to provide feedback foroptimizing control of the pump.

[0013] To add insult to injury, Morita teaches away from incorporatingmagnets on the vibrating arm(s). Morita also does not teach how tocontrol the operating frequency to match the pump self resonantfrequency nor does he teach directly or by inference how to control thecoil current.

[0014] Tune '710 teaches away from a self-optimizing pumping system inthat the function of the system described by Tune is the precise,periodic delivery of a fluid pharmaceutical into the vein of anambulatory patient. Optimizing flow for a given operating power levelwould be antithetical to the control objectives for such a system—theoutcome could be fatal. Tune's system, as described, is designed toreplicate the precise regimen/discipline of chemical therapy as it wouldbe practiced by clinicians in a clinical setting while allowing patientsto roam about and function more-or-less normally, unattended, innon-clinical environments.

[0015] Automation and control of fluid flow in Tune's system is based,primarily, on a scheme where the precise and periodic pumping of fluidis dependent on the precise and periodic displacement of the internalvolume of a resilient tube under the influence of a motor drivenplunger.

[0016] The internal volume of displaced tubing and not other factors(such as backpressure) determine the volume of fluid delivered to thepatient.

[0017] Rising and falling blood pressure level and/or the standing orsupine posture of the patient (and, hence, the fluid column height intowhich Tune's pump is operating) have little influence on the deliveredfluid volume. This insensitivity to such factors is a deliberate anddesirable feature of Tune's system. Tune isolates the delivered fluidvolume from influences such as those described in point 3 by deliberatemechanical design of the pumping mechanism. The design is inherentlyinsensitive to such influences because the moment of the plunger/tubingsystem is made very small such that the pump mechanism motor torque isrelatively unaffected by such influences. Because of mechanical designand control objectives, it is difficult to frame an argument for Tune'spump as having a varying self-resonance that is dependent on the pumpingconditions. In this sense, Tune teaches away from a pumping system thatcan be self-optimizing

[0018] Incorporation of the control elements as described by Tune et al.to refine the pump and controller as disclosed by Morita would notnaturally result in the self-optimizing system described by theApplicant. Hindsight would be required to selectively modify and applythe elements presented by both Tune and Morita to achieve a system asdisclosed by the Applicant. Hence, the Applicant respectfully submitsthat the disclosure made in this Application is not made obvious byMorita in light of Tune et al.

[0019] Enomoto '559, Point '204 Grant '986, Hase '439 Wang '293 and/orItakura '904 do not teach individually or in combination a pulsegenerator, a control system, nor any means for feedback control.

[0020] They also do not teach interrupting the drive current to createan opportunity (in the interval when the drive current is off) tomonitor the voltage produced in the electromagnet coil by the returningmotion of the magnet near the core poles. They also do not teachinterrupting the drive current to create an opportunity (in the intervalwhen the drive current is off) to monitor the voltage produced in theelectromagnet coil by the returning motion of the magnet near the corepoles.

[0021] Furthermore Enomoto and Point & Hase do not teach interruptingthe drive current to create an opportunity (in the interval when thedrive current is off) to monitor the voltage produced in theelectromagnet coil by the returning motion of the magnet near the corepoles. Enomoto also does not teach control of the drive frequency tooptimize pumping efficiency for varying pumping loads.

[0022] Sipin 517 teaches a separate pressure transducer (claim 15 (a)).Sipin teaches a system wherein flow control feedback is derived from aseparate transducer and not from analyzing a signal directly generatedby the pump mechanism. Sipin teaches a non-resonant pumping mechanism.Sipin does not teach a system for optimizing flow rate for a given pumpdrive current.

[0023] Brinkman '174 does not teach use of the pump mechanism as apressure transducer.

[0024] Brinkman teaches away from a pump structure that would allowgenerating a voltage in the electromagnet coil by the returning motionof the pump armatures.

[0025] O'Dougherty '582 also does not teach a pump, per se. O'Doughertydoes not teach a pump and a flow measuring device configured forautomatic control of flow rate or for automatic optimization of pumpingefficiency with varying pumping loads. O'Dougherty does not teach a flowmeasuring device with any provision for incorporating it into anautomatic control system. As claimed, O'Dougherty's flow analyzer has nomeans for deriving a signal that could be used in an automatic controlsystem.

[0026] Unfortunately none of the prior art devices singly or even incombination provide all of the features and objectives established bythe inventor for this system as enumerated below.

[0027] OBJECTIVES:

[0028] 1. It is an objective of this invention to provide method,devices and system for automatically optimizing a fluidic pump.

[0029] 2. Another objective of this invention is to provide method,devices and system for manually optimizing a fluidic pump.

[0030] 3. Another objective of this invention is to provide a sensor, amicroprocessor and a control feedback loop for optimum efficiency duringoperation.

[0031] 4. Another objective of this invention is that it be easy to useeven intuitive that requires little additional training.

[0032] 5. Another objective of this invention is that it be capable ofmultiple functions and uses.

[0033] 6. Another objective of this invention is that it beenvironmentally friendly.

[0034] 7. Another objective of this invention is that it be made ofmodular components and units easily interface-able to each other.

[0035] 8. Another objective of this invention is that it meets allfederal, state, local and other private standards, guidelines andrecommendations with respect to safety, environment, and quality andenergy consumption.

[0036] 9. Another objective of this invention is that it be elegantlysimple in concept and design.

[0037] 10. Another objective of this invention is that it be applicableto retrofit as well as OEM market.

[0038] 11. Another objective of this invention is that it be easy toinstall, de-install, transport and store.

[0039] 12. Another objective of this invention is that it be useable inall types of environmental conditions.

[0040] 13. Another objective of this invention is that it can be adaptedfor other related uses for pumping of gases and liquids

[0041] 14. Other objectives of this invention reside in its simplicity,elegance of design, ease of manufacture, service and use and evenaesthetics as will become apparent from the following brief descriptionof the drawings and concomitant description.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0042] a) FIG. 1-A is a block drawing of a representativeelectromagnetic reciprocating pump showing the major components.

[0043] b) FIG. 1-B is a graph showing the relationship between flow anddrive frequency for the type of pump mechanism depicted in 1-A.

[0044] c) FIG. 1-C is a graph showing the relationship between pump loadand the optimum drive frequency for the type of pump mechanism depictedin 1-A.

[0045] d) FIG. 2 is a drawing of representative circuitry for achievingpulsed drive with manual frequency and current (pulse-width) control.

[0046] e) FIG. 3 is a drawing of representative circuitry for drivingthe pump coil and for amplification and conditioning of the signalwaveform.

[0047] f) FIG. 4 is a Microsoft Excel plot showing the relationshipbetween the amplitude of the waveform of the signal produced by thereturn swing of the magnets and the fluid column height or pumping load.

[0048] g) FIG. 5 is a plot that shows representative components of thenominal signal waveform.

[0049] h) FIG. 6 shows various aspects of the signal waveform for anear-optimum drive frequency, a lower than optimum drive frequency and ahigher than optimum drive frequency. FIG. 6 also shows Least Squares Fittrend lines for the portions of the signal that would be analyzed forautomatic control.

[0050] i) FIG. 7 is a plot that shows representative components of thesignal waveform when the pumping capacity is exceeded.

[0051] j) FIG. 8 is a block diagram of the major elements andconfiguration for manual control.

[0052] k) FIG. 9 is a block diagram of the major elements andconfiguration for automa tic control.

DETAILED DESCRIPTION OF THE INVENTION

[0053] Automatic Optimizing Pump and Sensor System of this invention asshown in the drawings wherein like numerals represent like partsthroughout the several views, there is generally disclosed in FIG. 1 (a)drawing of a representative electromagnetic reciprocating pump showingthe major components. FIG. 1-B is a graph showing the relationshipbetween flow and drive frequency for the type of pump mechanism depictedin 1-A. FIG. 1-C is a graph showing the relationship between pump loadand the optimum drive frequency for the type of pump mechanism depictedin FIG. 1-A.

[0054] Electromagnetic reciprocating pumps are mechanical resonatorswith the resonate frequency being determined by mechanical design,variations from design introduced during manufacturing and by pumpingconditions.

[0055] In their principal application (aeration of aquariums to sustainaquatic life) these pumps are driven at the relatively constantfrequency of the Alternating Current power line (60 Hz, US). The pumpsare designed to be resonant at or near that frequency while the loadconditions vary only slightly about a “nominal” level—a nominal heightof the fluid column into which the pump is operating. As currentlydesigned, manufactured and marketed, these pumps can only operateoptimally when both the line frequency and fluid column height are atthe nominal design values. Measurement indicates that the pump mechanismresonate frequency is strongly dependent on pump load conditions andthat pumping efficiency—the rate of flow as a function of powerconsumption—is strongly influenced by the drive frequency.

[0056] Measurement also indicates that pumping efficiency decreasessharply when either the drive frequency or load conditions vary from thedesign nominal. Optimizing the pumping efficiency for a range of loadconditions requires control of the drive frequency. Once the drivefrequency is optimized, drive current can be reduced to produce requiredflow at the lowest possible power level.

[0057] The invention comprises a coil wound about a bipolar or tripolarcore, a diaphragm structure mechanically coupled to at least one armwith a magnet attached to one end of the arm and a controllerelectronically connected to the coil. The arm is vibrated under theinfluence of a periodic electromagnetic field to produce flow. The flowof current through the electromagnet is interrupted so that the magnetsare impelled during either a vacuum or a pressure stroke, but are notimpelled during the reciprocal stroke. A microprocessor houses thecontroller which analyzes amplitude and frequency components of a signalproduced in the electromagnet coil during the reciprocal stroke toprovide a pump flow rate, a pumping efficiency, a pumping load and aheight of the fluid column into which the pump mechanism is operating.The controller employs automatic feedback such that an operatingfrequency is controlled to match a self-resonant frequency of the pumpand a coil current is controlled to a minimum value required to providethe desired flow.

[0058] The microprocessor further comprises a pulse generator and asolid state switch that interrupts current flow through a pumpelectromagnet. The voltage waveform can be analyzed to deriveinformation for control of the drive frequency and drive current. Thecontrol can be used to optimize flow for a given operating power level,to optimize power consumption for a given required flow rate and/or tocontrol flow rate for varying operating conditions that fall within theperformance limits of the pump. In addition, the voltage waveform can beanalyzed to indicate the static (or dynamic) pressure or pump load. Fora given drive current, the voltage waveform has a consistentrelationship to the height of the fluid column into which the pump isoperating.

[0059]FIG. 2 is a drawing of representative circuitry for achievingpulsed drive with manual frequency and current (pulse-width) control andFIG. 3 is a drawing of representative circuitry for driving the pumpcoil and for amplification and conditioning of the signal waveform.

[0060]FIG. 4 is a Microsoft Excel plot showing the relationship betweenthe amplitude of the waveform of the signal produced by the return swingof the magnets and the fluid column height or pumping load.

[0061]FIG. 5 is a plot that shows representative components of thenominal signal waveform.

[0062]FIG. 6 shows various aspects of the signal waveform for anear-optimum drive frequency, a lower than optimum drive frequency and ahigher than optimum drive frequency. FIG. 6 also shows Least Squares Fittrend lines for the portions of the signal that would be analyzed forautomatic control.

[0063]FIG. 7 is a plot that shows representative components of thesignal waveform when the pumping capacity is exceeded.

[0064]FIG. 8 is a block diagram of the major elements and configurationfor manual control.

[0065]FIG. 9 is a hybrid diagram as combination of block diagram of themajor elements and configuration as well as a flow-chart for automaticcontrol.

[0066] By modifying the drive method for an electromagnetic type pumpsuch as those described in U.S. Pat. Nos. 4,154,559 and 4,170,439 thepump mechanism will also serve as a sensor. With the addition of aprocessing and control unit the pump/sensor configuration allowscontinuous automatic optimization of pumping efficiency as well as levelsensing. The processing and control unit is a microprocessor withappropriate Input and Output capabilities and resident firmware orsoftware that completes the implementation.

[0067] Many conventional electromagnetic air/fluid pump designs utilizediaphragms that are pulsated by an alternating mechanical force that isderived from the motion of permanent magnets under the influence of analternating magnetic field. To produce the field, a coil is wound oneither a bipolar or tripolar iron core and driven by an alternatingelectric current. The permanent magnet is alternately attracted to andrepelled by the core pole(s).

[0068] Referring to FIG. 1-A, various refinements to the pump structurehave been made to reduce vibration, noise and/or to increase the numberof ports but the basic configuration comprises: a frame 110 thatmechanically integrates the pump components; a coil 120 and core 160electromagnet assembly; a permanent magnet 130 affixed to the end of thedrive arm near the electromagnet 120, 160; a drive arm 140 with the endopposite the magnet affixed to flexible pivot point; and a diaphragmpump 150 attached to the frame 110 and to the drive arm 140 such that asthe arm 140 vibrates the diaphragm 150 pulsates and produce flow. Valvesand ports integral to the diaphragm 150 are not differentiated orlabeled.

[0069] In practice, these pumps are driven by the continuous 60 Hzsinusoidal AC service available from utility power companies (50 Hz insome countries other than the US). In their design and manufacture theyare made to pump most efficiently at or near the utility power frequencywhen they are operating at or near the nominal conditions of theirintended application range. As conditions vary from the nominal,efficiency and flow also vary. Off nominal pump performance may becomeso compromised that flow ceases well before the pump capacity isexceeded.

[0070] To illustrate, FIG. 1-B shows the effect on flow as the drivefrequency is varied above and below the nominal value for a 20 inchwater column load condition. In FIG. 1-B, drive frequency is plottedalong the horizontal (X) axis and flow (in milliliters/minute) isplotted along the vertical (Y) axis. Referring to FIG. 1-B, note thatFlow is reduced by 25% as the drive frequency is varied by about 7% offthe nominal. FIG. 1-C shows the relationship between pumping load andthe optimum drive frequency. In FIG. 1-C, drive frequency is plottedalong the vertical (y) axis and column height (in inches of water) isplotted along the horizontal(X) axis.

[0071] By driving these pumps with periodic pulses rather thancontinuous sinusoidal current (or by appropriately interrupting asinusoidal current), an opportunity is created in the interval betweenthe drive pulses to monitor the voltage produced in the coil 120 by thereturning motion of the magnet 130 near the core poles 160.

[0072]FIG. 2 shows representative circuitry for providing drive pulsesof varying frequency and widths. Transistor 210 is configured as aconstant current source charging capacitor 220. Voltage comparator 230compares the charge voltage on capacitor 220 and the level set by thepotentiometer control 240 labeled “Frequency”. When the charge level ofcapacitor 220 and the level set by control 240 are equal the astablemultivibrator (one-shot) 250 is triggered and produces a pulse with aduration set by potentiometer control 270 labeled “Current”.Concurrently, transistor 260 discharges capacitor 220 to cause the cycleto repeat. The astable multivibrator output pulse is buffered bytransistor 280 in an open collector configuration. The buffered output290 drives the complimentary current amplifier comprised of transistors315 and 320 shown in FIG. 3. The current amplifier provides a high gatecharging rate and rapid gate discharging rate for the solid state switch330 that interrupts current flow from the current source 370 through thepump electromagnet 340, 120, 160 (an inductor). Source current 370 flowsthrough 340, 120 when 330 is in the on condition (conducting). Currentflow is interrupted when 330 is in the off condition (non-conducting).

[0073] When current flow through 340, 120 is interrupted by 330, catchdiodes 350 and 360 allow fly-back current to re-circulate through theelectromagnet coil 340, 120 as the magnetic field collapses in theelectromagnet core 160. When the magnetic field has collapsed, all ofthe driving force to the permanent magnet 130 is expended, allowing thepermanent magnet 130 to swing back past the electromagnet 120, 340 core160 propelled by the returning force of the drive arm 140 and the springforce stored as back pressure in the pump diaphragm 150. As thepermanent magnet 130 swings back past the electromagnet 120, 340 core160 a voltage is induced in the electromagnet coil 340.

[0074] The voltage (signal) thus produced can be analyzed to derivesteering information for control of the drive frequency 240 and drivecurrent 270 to optimize flow for operating conditions within theperformance limits of the pump. In addition, the signal can be analyzedto indicate the back pressure or pump load. For a given drive current,this indication has a consistent relationship to the height of the fluidcolumn into which the pump is operating. This relationship 410 is shownin FIG. 4 with the fluid column height plotted along the X axis and thesignal amplitude plotted along the Y axis. Based on the Least SquaresFit straight line 420, this relationship appears to be linear. Thus thepump not only operates as a pump, but also as a level sensor.

[0075] Several prototypes have been constructed to verify thepracticality of this method. Pump electromagnet coils 120, 340 wererewound to achieve adequate magnetic flux with a low operating voltage(12 Volts, typical)—although higher voltage operation is perfectlyapplicable.

[0076] The drive circuitry (FIGS. 2 and 3) and pump (FIG. 1-A) werepowered by a 12 Volt power supply with a current capacity of 20 Amperes.The signal was clipped, amplified and level shifted by additionalcircuitry shown in FIG. 3 to make viewing on an oscilloscope displaymore convenient. In FIG. 3, amplifier 380 produces a signal 390 that isthe difference between the opposing electrical ends of the electromagnetcoil 120, 340. In this way, amplifier 380 removes the major commonvoltage that exists when switch 330 is open.

[0077] Amplifier 380 clips the signal to a zero potential when switch330 is closed. Bias diode 390 provides a small amount of level shiftingto assure that none of the signal of interest is clipped. The waveformsshown in FIGS. 5, 6 and 7 were obtained by processing acquired datawithin Microsoft Excel to approximate the action of the pre-processingcircuitry shown in FIG. 3 (data were offset, inverted, scaled andclipped).

[0078]FIG. 5 shows a representative (nominal) waveform derived from dataacquired during pump operation and processed using Microsoft Excel. InFIG. 5, time is displayed along the X axis and signal amplitude isdisplayed along the Y axis. The re-circulation time waveform 510 and thedrive pulse waveform 520 provide landmarks for the Operator that help inassessing the effects of adjustment of the frequency control 240 and thecurrent control 270. The signal of interest 530 appears between there-circulation time waveform 510 and the drive pulse waveform 520.

[0079] The electromagnet peak current was measured both by a currentprobe and by monitoring the voltage developed across a 0.1 Ohm resistor310 connected between the electromagnet solid state switch transistor330 emitter/source and circuit ground. Bipolar and Metallic OxideSemiconductor Field Effect (MOSFET) driver transistors have been usedwith good success. In the preferred embodiment the solid state switchtransistor 330 shown in FIG. 3 is a MOSFET.

[0080] Trial and error resulted in adoption of a two-diode 350 and 360catch scheme for the electromagnet coil. One catch diode is normallyused but multiple catch diodes shorten the current circulation time atfly-back by allowing a larger fly-back voltage to develop. During thetime that the catch diodes are conducting 510, the signal of interest ismasked. Two catch diodes 350 and 360 has proven to be a good compromisebetween efficient use of the energy stored in the electromagnet core160, 340 and unmasking of signal of interest 530.

[0081] With the modified pump electromagnet and prototype drivecircuitry, measurement confirmed that frequency control can be used tooptimize the pump efficiency (as measured by flow rate) over a widerange of pumping loads.

[0082] Measurement also confirmed that the 60 Hz pumps tested were notnecessarily most efficient at 60 Hz even at their nominal loadingconditions. Observation with an oscilloscope confirmed that the signalproduced by the return swing of the magnets was visible between drivepulses if the pulses were suitably short and that the length of thefly-back or re-circulation time is critical—too long and the signal ofinterest is masked. Observation also confirmed that the shape of thewaveform of the signal produced by the return swing of the magnets is afunction of drive current, pump load and drive frequency. Analysis usingMicrosoft Excel also confirmed that the waveform of the signal producedby the return swing of the magnets can be processed to produce feedbackcontrol to optimize the drive frequency and current.

[0083]FIG. 5 is a representative plot of the components of the nominalsignal waveform. Proceeding from left to right; division 1 on thehorizontal axis corresponds to the end of the drive pulse and beginningof the time that current re-circulates in the electromagnet 120, 160,340. Division 7 on the horizontal axis corresponds to the end of there-circulation time and the beginning of the return swing of thearmature magnets 130. Division 16 on the horizontal axis corresponds tothe end of the return swing and the beginning of the next drive pulse.The interval between division 1 and division 19 on the horizontal axisis the time between drive pulses (the reciprocal of the drivefrequency).

[0084]FIG. 6 waveform data were acquired by hand using the cursoracquisition feature of a Tektronix model 468 oscilloscope. The data werethen entered into Microsoft Excel spreadsheets and analyzed and plotted.Least Squares Fit straight lines 610, 620 and 63 were calculated andplotted along with the waveform data. The slope of the fitted lines 610,620, 630 varied with pump loading and changed sign on either side of theself-resonant (optimum) condition. FIG. 6-A shows a near-nominalwaveform with peak of the sinusoid roughly centered between the end ofthe re-circulation time and the beginning of the drive pulse. Note thatthe slope of the Least Squares Fit line 610 for the data in the signalinterval is near zero.

[0085]FIG. 6-B shows a waveform that obtains from too high a drivefrequency. Note that the slope of the Least Squares Fit line 620 for thedata in the signal interval is negative. FIG. 6-C shows a waveform thatobtains from too low a drive frequency. Note that the slope of the LeastSquares Fit line 630 for the data in the signal interval is positive.

[0086] Once optimized, the amplitude of the waveform of the signalproduced by the return swing of the magnets 130 is proportional to thepumping load for a specific drive current. Measurement and analysisconfirms that the amplitude of the waveform of the signal 530 producedby the return swing of the magnets 130 near the electromagnet core 160is proportional to the fluid column height or fluid level as describedearlier. The relationship 41 shown in FIG. 4 has a Least Squares Fitstraight line 420 with a coefficient of fit 430 (R') that is close to1.0. Data were taken while the pump air line outlet depth was increasedroughly every inch in a 24-inch high water column. The peak drivecurrent was approximately 2 Amperes (average drive current approximately0.150 Amperes).

[0087] Calibrating the system for fluid column height is straightforwardin that both intercept and slope can be derived from two or more datapoints. The constants are acquired by recording and analyzing thenominal condition waveforms (for one or more current settings) whilepumping into free air and into a fluid column with the maximumanticipated column height (e.g., empty tank, full tank).

[0088] As the column height is increased flow eventually stops whenthere is insufficient drive current. The column height and drive currentcan be increased up to a point where the maximum pumping capacity isexceeded. This condition is equivalent to a clogged air line and itresults in a unique waveform where the ending value of the fly-backvoltage is equal to (or nearly equal to) the peak value of the waveformbetween the landmarks described earlier. This clogged condition can bedetected automatically and the problem annunciated.

[0089]FIG. 7 is a representative plot of the drive and signal componentsof the waveform when the pumping capacity is exceeded. The off-nominalcharacteristic of the signal waveform in FIG. 7 is the ending amplitudeof the re-circulation voltage 710 that approximately equals the peaklevel of the return swing signal 720.

[0090] Manual Operation

[0091] By manually adjusting the drive frequency 240 in proportion tothe slope and sign of the Least-Squares-Fit straight lines 610, 620, 630flow could be optimized for varying operating conditions. In manualoperation both the operating drive frequency and drive current are setmanually by manipulating the potentiometer controls 240 and 270 shown inFIG. 2 (labeled “Frequency” and “Current”, respectively). In practice,the “Frequency” control 240 is set to a beginning value that correspondsto the nominal self resonant frequency of the pump mechanism asrepresented in FIGS. 1-A and 1-B (60 Hz is typical). Conventional meansfor monitoring the drive frequency can be used including a digitalfrequency meter or by observation of the interval between drive pulseson an oscilloscope display.

[0092] The beginning drive current is set by control 270 to any valuethat is below the saturation level for the pump electromagnet 120, 160,340. Conventional means for monitoring the drive current can be usedincluding a current probe and/or by observing the voltage developedacross the current sensing resistor 310 shown in FIG. 3 on anoscilloscope display. The preferred means of display for manual controlhas been to show both the “signal” 390 in FIG. 3 and the “current” 311in FIG. 3 concurrently on separate channels of a single oscilloscope,the oscilloscope time base being synchronized to the drive pulsesproduced at the output 290 of the pulse generator shown in FIG. 2. Theresulting display(s) provide an Operator with the information necessaryfor pump optimization and for deriving the height of the fluid columninto which the pump is operating. The signal and current waveforms areenhanced for display (and for signal processing) by the circuitry shownin FIG. 3.

[0093]FIG. 8 represents the process flow for manual control. TheOperator 81 manipulates the frequency and current controls 820, 240, 270of the pulse generator 830 driving the solid state switch 840, 330 thatinterrupts current flow from source 850 through the pump electromagnet860, 340, 160, 120. Signals generated by the current sensing resistor870, 310 and the pump coil 860, 340, 120 are conditioned for display onan oscilloscope 810 by circuitry 870 and 880 respectively. The Operator815, by observing the displayed waveforms 810, further manipulates thecontrols 820, 240, 270 to achieve the pumping optimization, the desiredrate of flow and/or the Operator derives from measurements of the signalwaveforms the height of the fluid column into which the pump isoperating. In this way the pump control loop is closed through theOperator.

[0094] Automatic Operation

[0095] For automatic operation, manual control of the operatingfrequency and operating current is augmented by a programmablecontroller (i.e., a microprocessor) that incorporates the means todigitize and analyze the signal waveforms and to generate drive pulsesat varying frequencies and of varying widths in relation to the analysisresults and to parameters that are established by the Operator. FIG. 9represents the process flow for automatic operation. The Operator 915enters parameters for the desired controlled conditions via controls anddisplays 920 (alpha/numeric keypad, LCD alpha/numeric display, typical).The controller 930 outputs pulses at a beginning nominal frequency andwidth to the solid state switch 940, 330 that interrupts current fromsource 950 through the pump electromagnet 960, 340, 160, 120. Signalsgenerated by the current sensor 970, 310 and the pump coil 960, 340, 120are conditioned by circuitry 980 and 990 respectively. The circuitrydelineated in FIG. 3 is merely representative. The conditioned signalsare digitized by elements 910 contained within the controller 930,analyzed according to appropriate algorithms embodied in the executablesoftware 911 and appropriate adjustments are automatically made toeither or both the operating frequency and operating current 912.

BEST MODE PREFERRED EMBODIMENT

[0096] The preferred embodiment of the invention includes areciprocating electromagnetic pump mechanism comprising one or more armswith magnet(s) attached to one end of the arm(s) such that the arm(s)may be vibrated under the influence of an electromagnetic field, thatfield being produced by the periodic flow of current in a coil woundabout a bipolar or tripolar core. The vibration of the arm(s) beingmechanically coupled to diaphragm(s) incorporating valves and ports suchthat a vacuum is created at one port and, simultaneously, a pressure iscreated at another port. The time the current flows through the coil ismade to be short so that the magnets are impelled during either thevacuum or pressure stroke but are not impelled during the reciprocalstroke, the reciprocal stroke being completed by the spring energystored in the arm/magnet/diaphragm system

[0097] During the reciprocal stroke the motion of the magnet(s) near thecore induces a voltage in the coil that is proportional to the velocityand the position of the magnet(s) traversing the core pole(s). Theamplitude and frequency components of the signal thus produced can beanalyzed by manual or automatic means to provide unequivocal indicationsof the pump flow rate, the pumping efficiency, and the height of thefluid column into which the pump is operating. Feedback is employed bymanual or automatic means such that the operating frequency iscontrolled to match the pump self-resonant frequency and the coilcurrent is controlled to a constant and appropriate value, the pumpingload or fluid column height can be known by measurement of the signalamplitude. The operating frequency is controlled to match the pumpself-resonant frequency. The pumping efficiency can be optimized bycontrol of the coil current to produce the highest possible flow ratefor a given operating power level. The operating frequency is controlledto match the pump self-resonant frequency. The fluid column height beingknown by measurement of the signal amplitude for a given coil currentand the coil current being otherwise controlled to produce and maintainthe signal amplitude at a desired level, the flow rate can be madeconstant for varying pumping loads.

[0098] The means for driving the coil of the reciprocatingelectromagnetic pump mechanism comprises a pulse generator and a solidstate switch (or switches) that interrupts current flow through the pumpelectromagnet. The operating current of the pump electromagnet (theelectromagnet being an inductor) is proportional to the time thatcurrent flows through it. The pulse generator is embodied in amicroprocessor with display(s) and controls and executing suitablesoftware such that pulses are produced at an output, the pulse frequencyand the pulse width being controlled manually or automatically. Manualor automatic control employing feedback are implemented throughadditional facilities embodied in the same microprocessor such thatsignals are digitized and analyzed so that the fluid column height ismeasured and displayed and/or the pumping efficiency is manually orautomatically optimized to produce the highest possible flow rate for agiven operating power level and/or the flow rate is manually orautomatically made constant for varying pumping loads.

ALTERNATE EMDBODIMENT

[0099] A further embodiment of the present invention is analternate-operating mode that sacrifices some short-term precision inthe flow control but improves the utilization of drive power (improvingpumping efficiency and capacity).

[0100] The alternate mode involves substituting an “H” bridge for thesimpler “open collector” or “open drain” type driver. With the “H”bridge, the pump mechanism can be driven on both strokes. Since drivingon both strokes will mask the signal, closed loop control is achieved byperiodically driving on only one stroke, processing the resulting signaland setting the drive frequency and current for some number ofsucceeding “both stroke” cycles. This mode changes (increases) thecontrol-loop time constant and may be inappropriate for someapplications but it would be fine for “optimizing” and measuring with(more) slowly changing pumping loads.

[0101] An example of a more slowly changing pumping load applicationwould be liquid holding tank level sensing where changes in level occurrelatively slowly. I would think a practical implementation for thismode would be 10 or more “both stroke” drive cycles followed by onesingle stroke drive and measurement cycle, and so on. The “H” bridgephasing to accomplish this would be easily handled by the microprocessoralready in the control loop.

[0102] For optimizing the aeration of a fish tank, either to control thelevel of oxygenation and compensate for slowly varying water columnheights (evaporation) or to consume the minimum power possible todeliver a required level of oxygenation (for power savings), or both, itmight be practical to go thousands of drive cycles before taking ameasurement. For this particular application it would also be desirableto operate the mechanism and control circuitry at power line voltagelevels. This would not be a problem.

[0103] Two additional improvements in the electromagnet are:

[0104]1) Profiling of the electromagnet pole faces to from an arc thatpermits maintaining a small and constant gap between the poles and thepermanent magnets that are attached to the swing arms. This makes moreefficient use of the flux developed by the electromagnet.

[0105]2) Selection of the electromagnet core material permeability tomatch the short duration of the drive pulse—that is, select a materialthat will allow flux to build more rapidly than the soft iron typicallyused. This would result in a shorter time for collapsing of the magneticfield and has, a shorter recirculation time of the back EMF through thecoil and hunt diodes. The shorter recirculation time would allow more ofthe signal to be observed when the pumping loads are in the higher range(where he optimum frequency for the pump drive is in the higher range).

[0106] The inventor has given a non-limiting description of the AirBorne Fire Fighting system of this invention. Due to the simplicity andelegance of the design of this invention designing around it is verydifficult if not impossible. Nonetheless many changes may be made tothis design without deviating from the spirit of this invention.Examples of such contemplated variations include the following:

[0107] a) The shape and size of the various members and components maybe modified.

[0108] b) The power, capacity, aesthetics and materials may be enhancedor varied.

[0109] c) Additional complimentary and complementary functions andfeatures may be added.

[0110] d) state switch means may be employed for interrupting currentflow through the electromagnet coil)

[0111] e) Permanent magnets and electromagnet (stationary permanentmagnet and moving electromagnets) may be interposed.

[0112] f) Other changes such as aesthetics and substitution of newermaterials as they become available, which substantially perform the samefunction in substantially the same manner with substantially the sameresult without deviating from the spirit of the invention may be made.

[0113] Following is a listing of the components used in this embodimentarranged in ascending order of the reference numerals for readyreference of the reader.

[0114] 110=Frame

[0115] 120=Inductive coil

[0116] 130=Permanent magnet

[0117] 140=Drive arm

[0118] 150=Diaphragm pump

[0119] 160=Electromagnet

[0120] 210=Transistor

[0121] 220=Capacitor

[0122] 230=Comparator

[0123] 240=Potentiometer (Voltage)

[0124] 250=Astable multivibrator (One shot)

[0125] 260=Transistor

[0126] 270=Potentiometer (Current)

[0127] 280=Transistor

[0128] 290=Buffered output

[0129] 310=Resistor

[0130] 311=Comparator output

[0131] 312=Diode

[0132] 315=Amplifying transistor

[0133] 320=Amplifying transistor

[0134] 330=MOSFET Transistor

[0135] 340=Electromagnet

[0136] 350=Catch diode

[0137] 360=Catch diode

[0138] 370=Electromagnet

[0139] 380=Amplifier

[0140] 390=Differential output signal

[0141] 410=Signal depth relationship curve

[0142] 420=Least squares fit of signal depth relationship

[0143] 510=Recirculation time waveform

[0144] 520=Drive pulse waveform

[0145] 530=Intermediate Signal of Interest

[0146] 610=Least squares fit for optimum drive frequency

[0147] 620=Least squares fit for low drive frequency

[0148] 630=Least squares fit for high drive frequency

[0149] 710=Ending amplitude of re-circulation voltage

[0150] 720=Peak level of return swing signal

[0151] 810=Display oscilloscope

[0152] 815=Operator

[0153] 820=Frequency and current control

[0154] 830=Pulse generator

[0155] 840=Solid state switch

[0156] 850=Current source

[0157] 860=Pump electromagnet

[0158] 870=Current sensor circuitry

[0159] 880=Signal conditioning circuitry

[0160] 890=Signal conditioning circuitry

[0161] 910=Signal conversion means

[0162] 912=Frequency and Pulse width control

[0163] 915=Operator

[0164] 920=Controls and displays

[0165] 930=Controller

[0166] 940=Solid stage switch

[0167] 950=Current source

[0168] 960=Pump inductive coil

[0169] 970=Current sensor circuitry

[0170] 980=Signal conditioning circuitry

[0171] 990=Signal conditioning circuitry

DEFINITIONS AND ACRONYMS

[0172] A great care has been taken to use words with their conventionaldictionary definitions. Following included here for clarification.

[0173] 3D=Three Dimensional

[0174] DIY=Do It Yourself

[0175] Integrated=Combination of two entities to act like one

[0176] Interface=Junction between two dissimilar entities

[0177] Symmetrical=The shape of an object of integrated entity which canbe divided into two along some axis through the object or the integratedentity such that the two halves form mirror image of each other.

[0178] While this invention has been described with reference toillustrative embodiments, this description is not intended to beconstrued in a limiting sense. Various modifications and combinations ofthe illustrative embodiments as well as other embodiments of theinvention will be apparent to a person of average skill in the art uponreference to this description. It is therefore contemplated that theappended claim(s) cover any such modifications, embodiments as fallwithin the true scope of this invention.

The Inventor claims:
 1. A reciprocating electromagnetic pump comprising:a) a coil wound about a core to form an electromagnet; b) a diaphragmstructure incorporating inlet and outlet check valves and a pair ofcorresponding inlet and outlet ports connected to said electromagnet;(c) at least one first arm disposed with a magnet at one end and atleast one second arm mechanically coupled to said diaphragm; d) a solidstate switch means for interrupting current through said electromagnet;and e) a microprocessor comprising a pulse generator connected to saidsolid state switch.
 2. The reciprocating electromagnetic pump of claim 1, wherein said first arm and said second arm are each disposed aroundsaid diaphragm structure as a means for vibrating said diaphragmstructure under the influence of an electromagnetic field.
 3. Thereciprocating electromagnetic pump of claim 1 , wherein said coil iswound about said core that is formed to position both poles at the sameend of the coil.
 4. The reciprocating electromagnetic pump of claim 1 ,wherein said coil is wound about said core to form three polespositioned at the same end of said coil.
 5. The reciprocatingelectromagnetic pump of claim 1 , wherein the pulse generator employsautomatic feedback such that an operating frequency is controlled tomatch a self-resonant frequency of the pump and a coil current iscontrolled to a constant and an appropriate predetermined value.
 6. Thereciprocating electromagnetic pump of claim 5 , wherein said automaticfeedback of the controller controls the operating frequency to maximizethe flow rate for a predetermined operating power level.
 7. Thereciprocating electromagnetic pump of claim 6 wherein: a) said automaticfeedback control automatically optimizes the operating frequency; and b)said coil current is automatically controlled to produce and maintainthe signal amplitude at a desired predetermined constant level.
 8. Thereciprocating electromagnetic pump of claim 1 , wherein said automaticfeedback control is embodied in a microprocessor comprising: a) a pulsegenerator with software controlled pulse rates and pulse widths; b) asignal digitizer connected to said pulse generator; c) a plurality ofdisplays and controls under the control of a stored program as a meansfor producing a plurality of pulses as the output of saidmicroprocessor; and d) a means for automatically controlling pulsefrequency and a pulse width connected to said pulse generator.
 9. Thereciprocating electromagnetic pump of claim 1 , wherein said first armand said second arms are vibrated under the influence of anelectromagnetic field.
 10. The reciprocating electromagnetic pump ofclaim 1 wherein the operating frequency of said electromagnet isadjusted to maximize the flow rate for a predetermined operating powerlevel and the drive current of said electromagnet is adjusted by varyingthe length of time current flows through said coil.
 11. A process ofreciprocating electromagnetic pump comprising the steps of: a) making anelectromagnet by winding a coil about a core; b) building a diaphragmstructure by incorporating an inlet and an outlet valve and a pair ofcorresponding inlet and outlet ports; c) adding at least one arm with amagnet attached to one end of said arm; d) mechanically coupling saidarm to said diaphragm; e) interrupting current flow through saidelectromagnet; f) electronically connecting a pulse generator as a meansfor frequency control and a pulse width control; g) manually controllingthe operating frequency and coil current through said coil; h) vibratingsaid arm under the influence of an electromagnetic field; i) inducing avoltage in said coil; j) electronically enhancing and displaying theresultant signal from step (j) supra; k) analyzing the amplitude andfrequency components of said signal; l) observing the oscillographicdisplay and controlling the operating frequency to maximize the flowrate for a predetermined operating power level; and m) controlling thecoil current to vary the flow rate.
 12. The process of reciprocatingelectromagnetic pump of claim 11 , wherein two arms are disposed whereineach of the arms has a magnet attached to one end of the arm forvibrating the arm under the influence of an electromagnetic field. 13.The reciprocating electromagnetic pump of claim 11 , wherein said coilis wound about a bipolar core.
 14. The process of reciprocatingelectromagnetic pump of claim 9 , wherein said coil is wound about atripolar core.
 15. The process of reciprocating electromagnetic pump ofclaim 11 , wherein said pulse generator employs automatic feedback suchthat an operating frequency is controlled to match a self-resonantfrequency of the pump and a coil current is controlled to a constant andan appropriate predetermined value.
 16. The process of reciprocatingelectromagnetic pump of claim 15 , wherein the automatic feedback of thecontroller controls the operating frequency to maximize the flow ratefor a predetermined operating power level thereby optimizing the pumpingefficiency.
 17. The process of reciprocating electromagnetic pump ofclaim 11 , wherein: a) the automatic feedback control optimizes theoperating frequency and; b) the fluid column height is determined from ameasurement of the signal amplitude for a given coil current; and c) thecoil current is controlled to produce and maintain the signal amplitudeat a desired predetermined level, the flow rate is constant for varyingpumping loads.
 18. The process of reciprocating electromagnetic pump ofclaim 11 wherein the operating frequency of said electromagnet isadjusted to maximize the flow rate for a predetermined operating powerlevel and the drive current of said electromagnet is adjusted by varyingthe length of time current flows through said coil.
 19. An automaticoptimizing pump and sensor system for controlling and maintaining theconstant flow of a gas comprising: a) an electromagnet connected to apump; b) a current source connected to said pump; c) a microprocessormeans for controlling pulse width and frequency connected to said pulsegenerator; d) a pulse generator interfaced to said microprocessor; e)mans for sensing current through said electromagnet of said pump; f) asolid state means for interrupting current through said pump; and g)means for controlling the operating frequency and coil current throughsaid electromagnet.
 20. The automatic optimizing pump and sensor systemfor controlling and maintaining the constant flow of a gas of claim 19wherein the operating frequency of said electromagnet is adjusted tomaximize the flow rate for a predetermined operating power level and thedrive current of said electromagnet is adjusted by varying the length oftime current flows through said electromagnet.